This invention relates to a magnetic head having its magnetic path constituted by a magnetic metal film, and a method for manufacture thereof. More particularly, it relates to a magnetic head having its coil formed by a thin film process, and a method for manufacture thereof.
As magnetic heads for VTRs, a so-called metal-in-gap type magnetic head, in which a magnetic metal film is formed on the magnetic gap forming surface of the ferrite magnetic core, or a laminated magnetic head having a magnetic metal film sandwiched between non-magnetic ceramic layers, is currently employed. For coping with the future tendency towards higher picture quality and digitalization, higher electro-magnetic conversion characteristics need to be achieved for higher frequencies. Besides, plural magnetic heads need to be loaded on a small-sized drum.
However, the above-mentioned metal-in-gap magnetic head has a larger impedance and is not suited to application in a higher frequency range. On the other hand, it is necessary with the laminated magnetic head to decrease the thickness of the magnetic metal film of the magnetic path in conjunction with decrease in the track width brought about by the recording with an increasingly high recording density. The result is the lowering of the playback efficiency and certain limitations placed on the increase in the number of magnetic heads.
There has hitherto been proposed a magnetic head in which, for successfully coping with signals in the high frequency range, the magnetic path constituted by the magnetic metal film is reduced in area as compared to that with the conventional VTR head, and in which a thin film coil is formed on the magnetic gap forming surface using the thin film forming technique, as disclosed for example in JP Patent Kokai Publication No. 63-231713 (1988).
However, it becomes necessary with such construction of the magnetic head to provide a space for accommodating the thin film coil in the counterpart magnetic core provided facing the magnetic core having the thin film coil formed thereon.
If the space is formed by a machining operation, an opening which needs to be plugged with glass or the like is necessarily formed on the surface of the magnetic head on which the magnetic recording medium is slid.
During the glass plugging process, which is an indispensable process, molten glass flows on the thin film coil portion, thus raising the problems such as line breakage or shorting.
Besides, since there is a risk of damages done or the stress applied to the magnetic gap forming surface of the substrate during fabrication of the thin film coil, there is raised a problem in connection with difficulties in maintaining gap accuracy. Thus it is difficult to apply the prior-art technique to a multi-channel magnetic head for which strict gap accuracy is a requirement.